DESCRIPTION: In this application, studies are proposed to determine the solution structures of a series of molecules related to the anticodon loop of the tRNA3lys primer for the synthesis of the minus strand of HIV DNA using NMR. The PI will synthesize RNA 17-mers corresponding to the stem-loop of the anticodon loop structure. He will substitute within this series naturally occurring modified nucleosides at the same site that they appear in tRNA3lys. The influence of these modifications on the structure, stability and RT binding of the stem loop will be evaluated. The investigator also states that he intends to investigate the effect of RNA modification on RNA-RNA interactions that may be important for primer interactions with complimentary RNA templates. Traditional 2D NMR methods along with newer homonuclear and heteronuclear 3D NMR experiments will be used to assign RNA resonances and to derive structural information. Distance geometry and molecular dynamics calculational methods will be used to convert NMR structural constraints into defined 3D structures.